[sascha_sl]

wireguard-go

https://git.zx2c4.com/wireguard-go/about/

[bauerd]

There is also https://github.com/cloudflare/boringtun

Edit: Someone running wg in userspace and can share some experiences with either implementation?

[loeg]

The userspace wireguard-go implementation is slower than the kernel one. Some (I don't know how much) of that is the userspace <-> kernel barrier, but they're also totally different implementations (Go vs C).